The foreign secretary and his French counterpart, Bernard Kouchner, met Joseph Kabila for about an hour and a half in the Congolese capital, Kinshasa.

The two were due to continue on to the eastern town of Goma on the Rwandan border, where a ceasefire continued to hold after violence earlier this week. Later, they will travel to the Rwandan capital, Kigali, for talks with the country's leader, Paul Kagame.

"We had a good meeting ... The key theme of our discussion has been the need to implement the agreements that have already been made," Miliband said after the meeting, according to the AFP news agency.

"Around the world, people are seeing the makings of a humanitarian crisis and it's vital that politics is used to reverse a further round of deaths and killings."

In Goma, tension remained high amid a fragile ceasefire as Tutsi rebel troops led by General Laurent Nkunda laid siege at the doorstep of the capital of Nord Kivu province.

Government forces abandoned Goma on Wednesday as the rebels advanced, leaving just 850 United Nations peacekeepers between Nkunda's forces and Goma.

Miliband and Kouchner arrived in Congo as Gordon Brown, the prime minister, spoke of his fears of a developing humanitarian disaster in the region.

"My worry is about the thousands of people being displaced at the moment by the violence that is taking place," Brown said.

Aid agencies and the UN have warned of impending disaster for thousands of people caught up in the fighting between the Congolese army and the rebel force, which is backed by neighbouring Rwanda's Tutsi leadership.

The UN refugee agency said it had received credible reports that rebels had looted and burned camps for displaced people. "We are extremely concerned about the fate of some 50,000 displaced people living in these camps, which include the UNHCR-administered sites of Dumez, Nyongera and Kasasa," the spokesman Ron Redmond said.

An estimated 1 million people have been forced from their homes in North Kivu, a province of 5 million that borders Rwanda, after two years of violence. The former Belgian colony, which is rich in copper, cobalt, gold and diamonds, was at war from 1998 until 2003. Around 220,000 people have been displaced since the latest round fighting broke out in August.

Referring to the Goma peace accord reached in January this year, Kouchner said today: "We do not have to redefine the peace protocol ... That has already been done."

Under the agreement, which has not been implemented, a ceasefire would be enforced and all armed groups in the region would be disarmed.

The junior foreign minister, Lord Malloch Brown, said today that Britain might need to send troops to the area if talks failed. He said the UK and other European powers could not stand back if the fighting between government and rebel forces erupted again.

"We have certainly got to have it [a British force] as an option which is developed and on the table if we need it," he told the BBC. He, however, stressed that the deployment of EU troops was a last option if all else failed.

Charities have warned that unless supplies reach refugees hundreds could be at risk of dying of starvation and disease. Save the Children said today that a team, including health and nutrition experts, was back in Goma after being withdrawn earlier this week and was making an emergency assessment of the needs of the displaced there.

"The ceasefire around Goma seems to be holding and we are taking advantage of the precarious lull in the fighting to attempt to assess the situation so that we can target those in need with emergency feeding and clean water. We need to find out who is where and in what numbers so that we can help them," said the spokesman Dominic Nutt.